Fwiw my car is now a year and 6000 miles old.
When in EV mode, there is a noise that sounds similar to an underground train pulling away (low pitched 'moaning' type noise) that increases in frequency as speed increases, but also gets quieter, disappearing completely at about 20mph. Above that, there is an obvious but non-intrusive whine. With the windows open it is MUCH more obvious especially if you are driving next to a wall. This is obviously high speed gear noise, not motor noise, as it doesn't change when it changes gear at about 55mph, in spite of the motor speed dropping from about 9k down to 5k rpm.
Doesn't seem to have changed in any way since picked the car up so I just assumed it was normal for the vehicle.
What IS irritating however, is that I have a kind of 'jerky' acceleration in 'auto' mode - feels like a misfire but I'm assuming if it was, I would have a warning light by now. It's not the well known 52mph flat spot, just hesitation.... Its as if I was moving the accelerator up and down a little while accelerating. Anyone else noticed this? Dealer denies there's any problem although to be fair sometimes it's worse than others.